The invention relates to an arrangement for coupling optoelectronic components and optical waveguides to one another using a carrier substrate, at least one optoelectronic component or one optical waveguide being secured on the carrier substrate and at least one lens being provided which has an essentially planar surface and a spherical surface located opposite the planar surface.
German Published Patent Application DE 35 43 558 A1 discloses an optoelectronic coupling arrangement in which light conducted through an optical waveguide is coupled to a photo-detector. Optical waveguide and photodetector are secured on a carrier substrate. The coupling is carried out via an optical deflection component. The depressions for mounting the optical components can be produced, for example, by anisotropic etching. If the light emerging from the optical waveguide has a large angular divergence, a low-loss coupling to the photodetector can be achieved by a lens. In the above-mentioned published patent application in the proposed arrangement a hemispherical lens is arranged between the optical waveguide and the photodiode. The planar surface of the hemispherical lens is constructed as a deflection element and the lens is simultaneously used for focusing.
For focusing the beam, it is also known to use Fresnel lenses or spherical lenses. The production of Fresnel lenses on a carrier substrate, for example a silicon surface, requires an increased expenditure with additional process steps. However, Fresnel lenses have the advantage of a flat structure. Spherical lenses can be inserted into anisotropically etched depressions which are produced during the micromechanical structuring, necessary anyway, of the carrier material. They have the disadvantage that either they project beyond the substrate surface or, in relation to the optically effective surface, they need very large depressions to accommodate them, as a result of which the assembly of the photodiode is impaired.
Whereas, in the case of an optical waveguide-photodiode coupling, because of the relatively large tolerances, a purely passive adjustment is possible using mounting structures made from anisotropically etched silicon, in the case of coupling an optical waveguide to a laser, a sufficiently high accuracy cannot be achieved by passive adjustment using the anisotropic etching technique. To achieve a coupling between laser and optical waveguide, at a high input coupling efficiency, an imaging optics unit is necessary because of the mode field diameters of different sizes. Adjustment between optical waveguide and laser should be possible.